Atom The smallest unit of matter This is a carbon atom. How small is small? 1 Atom of Helium Diameter = 50 picometers (1/1,000,000,000,000) Mass = 1.67 x 10-27 kilograms Atoms most common in living organisms: carbon nitrogen hydrogen oxygen

Subatomic Particles: The parts of the atom Electron cloud: Space around the nucleus which has “levels” Location of ……. Nucleus: Center of the atom Location of……. Protons Neutrons electrons 1st level: 2 electrons 2nd level: 8 electrons 3rd level: 8 electrons

Particle Charges Protons have a positive charge (+) Neutrons have no charge (0) Electrons have a negative charge (-)

Atomic Number The number of protons an atom has. This number never changes! It is also the number of electrons a neutral atom contains

Atomic Mass Number of protons and neutrons in the nucleus Atomic Mass = Protons + Neutrons Electrons are too small to contribute much to the mass

Drawing Atoms Draw the Nucleus Add protons (+) and neutrons (o) into the nucleus Draw at least one electron level. Add electrons remembering the number each level can hold; you may need to add more electron levels 1st: 2 electrons 2nd: 8 electrons 3rd: 8 electrons

Atomic Structure & The Periodic Table

Periodic Table of Elements A chart of all elements known to man. Arranged in rows and columns. In order of atomic number.

Periodic Table of Elements Element – a substance made of only one kind of atom Example: Carbon Atoms can combine to make elemental carbon in the form of coal or diamonds. Chemical Symbols: Letters that represent the elements C-carbon H- hydrogen N- Nitrogen O-Oxygen P- Phosphorous

Shows information about each element Atomic Number Average Atomic Mass Number will be shown as a decimal. Why? Average of all the isotopes of that element in nature The actual Atomic Mass is not on the table- just an average

Mass Number always a whole number NOT on the Periodic Table! mass # = protons + neutrons always a whole number NOT on the Periodic Table! Neutron + Electrons Nucleus Proton Nucleus Carbon-12 Neutrons 6 Protons 6 Electrons 6

Isotopes of Carbon Neutron + Electrons Nucleus Nucleus Proton Proton Neutrons 6 Protons 6 Electrons 6 Electrons Carbon-14 Neutrons 8 Protons 6 Electrons 6 Nucleus

Chemical Compounds Substances made from 2 or more elements in defined proportions are called compounds Formed by chemical bonds Described by a chemical formula H2O 2 Hydrogen, 1 Oxygen NaCl 1 Sodium, 1 Chlorine Mg(OH)2 1 Magnesium, 2 Oxygen, 2 Hydrogen

Chemical Bonding Atoms interact with each other to form chemical compounds Only the outermost ELECTRONS of the atoms are involved – AKA: Valence Electrons

Thursday Covalent Bonding Video If you want more practice before your quiz tomorrow… Bonus Opportunity! Water Fact Sheet CW/HW: Read and Notes 2-2 (Due Friday)

Ban Dihydrogen Monoxide Bonus Read brochure Type a paragraph explaining what this substance really is and how you know. Why are the claims in the brochure true, but impossible? Explain why we can’t ban it!

Examples:

Stability An atom is considered stable when its outermost energy level is “filled” with electrons To achieve stability, atoms will gain, lose or share electrons

Ionic Bonds Bond where electrons are transferred from one atom to another (gain or lose) Ions (charged atoms) are held together by their charges. Example: Na+ Cl-

Animations ionic bonding animation http://www.bing.com/videos/search?q=ionic+bonding+animation&FORM=HDRSC3#view=detail&mid=D0981F9E5767EE5FB214D0981F9E5767EE5FB214

Bond in which 2 atoms share electrons Covalent Bonding Bond in which 2 atoms share electrons Atoms can share: 2 electrons (single bond) 4 electrons (double bond) 6 electrons (triple bond) Examples H2O or CO2

How to show a covalent bond 1st draw a dot diagram for each element in the compound Use dot diagrams to show sharing of valence electrons between atoms

Chapter 1 Test Summary 3rd Period 4th Period 5th Period Average 83% 81% 85% # of A’s 4 # of B’s 14 10 17 # of C’s 7 5 2 # of D’s 3 1 #of F’s Highest Score 91% 93% 94% Lowest Score 70% 68% 69%